Thom Tillis, the North Carolina House speaker, won the state's Republican Senate primary on Tuesday, setting up a battle against Democratic incumbent Sen. Kay Hagan in the fall.

Tillis, considered the GOP establishment's candidate, topped Tea Party-aligned candidate Greg Brannon and pastor Mark Harris. Four other Republicans also sought the nomination.

Tillis had the backing of the U.S. Chamber of Commerce, the National Right to Life Committee and former presidential candidate Mitt Romney. National party leaders have targeted Hagan as part of their effort to try to gain control of the Senate.

Hagan, whom Republicans have made a top target in their drive to win a Senate majority in the fall, won renomination over a pair of rivals with about 80 percent of the primary vote.

Tillis, giving his nomination victory speech, continued his criticism of Hagan, saying she's too closely aligned with Senate Majority Leader Harry Reid and has failed to halt President Obama's most destructive policies, chiefly the federal health care overhaul. Hagan voted for the law.

"Our republic was founded on separate but equal branches, a system with checks and balances," Tillis told cheering supporters at a Charlotte hotel. "But Kay Hagan hasn't provided any balance whatsoever when it's come to having a check on Obama. She's done nothing but abandoned her post for the last six years."

Tillis scarcely had time to savor his victory before the Democrats unloaded on him Tuesday night.

"No one in the country has done more for the Koch brothers than Thom Tillis — cutting public education nearly $500 million, cutting taxes for the wealthy while refusing pay raises for teachers and killing an equal pay bill," the party's Democratic senatorial committee said in a statement referring to the billionaire businessman brothers whom party leaders hope to make into national whipping boys in the fall campaign.

The National Rifle Association countered for Tillis, saying in a statement of its own that "Thom has long been one of most effective gun rights advocates in North Carolina."

Hagan is among the Democrats' most vulnerable incumbents in a campaign season full of them, a first-term lawmaker in a state that is ground zero in a national debate over the health care law that she and the Democrats voted into existence four years ago. Americans for Prosperity, a group funded by the billionaire Koch brothers, has run about $7 million worth of television commercials criticizing Hagan for her position on the law.

Hagan has portrayed herself as a middle-of-the-road U.S. senator who fights for the middle class and veterans and would prevent out-of-state conservatives from essentially buying a Senate seat with their ads criticizing her.

"This election is a simple choice between two very different records. Thom Tillis has spent his time in Raleigh pushing a special interest agenda that has rigged the system against middle-class families," Hagan said in a news release. She added: "North Carolinians know that I am the only candidate in this race who will put our state's needs ahead of what the special interests want."

Tillis and other Republicans said Hagan and a PAC backing Senate Democrats were trying to torpedo Tillis' candidacy and get a perceived weaker nominee, pointing to similar schemes in Nevada in 2010 and Missouri in 2012. Tillis has benefited from millions of dollars in advertising from outside groups critical of Hagan, particularly for her support of the federal health care overhaul law.

By receiving endorsements from National Right to Life and the National Rifle Association, Tillis was able to advertise credentials seen as favorable by potential supporters of Harris and Brannon. Harris is the former president of the North Carolina Baptist State Convention and was a chief spokesman for a group that worked successfully to get the 2012 constitutional amendment passed banning gay marriage. But even Tillis had a role in the amendment, leading the House when it agreed to put the amendment on the statewide ballot.